Latching assembly with magnetic locking

ABSTRACT

A latching assembly for a door swingable toward and away from a doorjamb or the like between a closed and an open position, comprising a pair of latch members mounted on the door and jamb, respectively, and relatively movable between an engaged latching position and a disengaged unlatched position. Each latch member includes one or more latching surfaces engageable with a latching surface on the other latch member when in the latched position preventing movement of said door relative to said doorjamb. Permanent magnet holding means is provided for holding or locking said latching members in said latched position, and selectively controlled electromagnetic means is used for producing a magnetic unlocking force with a polarity opposing that of said permanent magnet means for unlocking and relatively moving said latching members out of said latched engagement when said door is to be opened.

United States Patent Wang [451 Apr. 25, 1972 [541 LATCHING ASSEMBLY WITH 3,312,492 4/1967 Remhot ..292/201 MAGNETIC LOCKING Primary Examiner-Stanley N. Gilreath [72] Inventor: William S. Wang, Marina Del Rey, Calif. Assistant McCarthy [73] Assignee: Consolidated Controls Corporation, Attorney-Mason Kolehmainen' Rathbum & wyss Be 57 ABSTRACT [22] Filed: Jan. 15, 1970 Appl. No.: 3,132

A latching assembly for a door swingable toward and away from a doorjamb or the like between a closed and an open position, comprising a pair of latch members mounted on the door and jamb, respectively, and relatively movable between an engaged latching position and a disengaged unlatched position. Each latch member includes one or more latching surfaces engageable with a latching surface on the other latch member when in the latched position preventing movement of said door relative to said doorjamb. Permanent magnet holding means is provided for holding or locking said latching members in said latched position, and selectively controlled electromagnetic means is used for producing a magnetic unlocking force with a polarity opposing that of said permanent magnet means for unlocking and relatively moving said latching members out of said latched engagement when said door is to be opened.

11 Claims, 13 Drawing Figures LATCIIING ASSEMBLY WITH MAGNETIC LOCKING The present invention relates to a new and improved magnetic latching assembly, and more particularly to a latching as sembly wherein magnetic forces are used to hold or lock a pair of mechanically engageable latch members in latched engagement.

The magnetic latching assembly of the present invention is particularly well suited for application in modern aircraft for latching doors or closure panels on compartments containing oxygen equipment and masks and other emergency supplies for the passengers. In this specific application it is desirable that the latching assembly be hidden or generally unaccessible to the passenger and preferably mounted on the inside of the door or closure member within the compartment which contains the oxygen mask. Normally, unlatching is accomplished by electrical means actuated by the pilot of the aircraft; in addition, however, means must be provided whereby a pas senger, with proper instruction, can manually unlatch the latch assembly from outside of the compartment so that in cases of emergency, when the normal electrical unlatching system fails, the door can be opened and fast access can be had to the emergency oxygen equipment inside the compartment.

The latching assembly of the invention is arranged so that the latching or holding means, which holds and maintains the door in a closed or shut position, is not dependent on magnetic force but instead holding forces are established by a positive mechanical latching engagement between one or more latching surfaces on a pair of cooperating latch members and thus the latching assembly is able to withstand considerable G loading, such as might be caused by rapid aircraft acceleration and deceleration or by other forces, such as prying or hammering on the door by a passenger. The latching assembly of the present invention is normally unlatched by a controlled electrical impulse delivered at the desired time, and the energy of the impulse may also be used to aid in opening the door.

The previously described features are objects of the present invention, and it is another object of the invention to provide a new and improved door latching assembly in which permanent magnet means is used to provide a holding or locking force for retaining a pair of latching members in positive mechanical latched engagement.

Another object of the invention is to provide a latching assembly of the character described wherein unlocking of the engaged latch members out of latched position is accomplished by electromagnetic means developing a force in opposition to the holding force of said permanent magnet means.

Another object of the present invention is to provide a new and improved door latching assembly of the character described using electromagnetic force for unlocking the latch members, which force is also effective to aid in opening the door with which the latching assembly is used.

Another object of the present invention is to provide a new and improved latching assembly which is completely hidden within a compartment on the inside of an access door thereof, yet which may be latched or unlatched from outside of the compartment by means of a tool or finger inserted through a slot or opening in the door or compartment wall.

Another object of the invention is to provide a new and improved latching assembly of the character described including means for visually indicating when the latching assembly is in an unlatched position, even though the door is still closed.

Another object of the invention is to provide a new and improved latching assembly of the character described wherein mechanical latching or holding force is attained with spherical latching surfaces.

Another object of the invention is to provide a new and improved latching assembly of the character described wherein one of the latch members includes a spheroid mounted adjacent the free outer end of a deflectable support member.

Another object of the invention is to provide a new and improved latching assembly described in the preceding object including an opposite latching member comprising socket forming means for receiving said spheroid and including a plurality of spheroids therein in annular ringlike array for movement radially inwardly and outwardly into and out of latching engagement.

Another object of the invention is to provide a new and improved latching assembly of the character described which is reliable and simple in operation, low in cost, and which can be mass produced in volume yet meet stringent safety test requirements.

Briefly, the foregoing and other important objects and advantages of the present invention are accomplished by providing a new and improved latching assembly having a pair of latch members mounted on a door and doorjamb, respectively, and movable relatively between an engaged, latched position and disengaged, unlatched position. Permanent magnet holding or locking means is provided for normally maintaining the latch members in an engaged latched condition, and electromagnet means is provided for momentarily opposing and nullifying the magnetic holding force with a force of opposing polarity for moving the latch members to an unlatched position, permitting the door to be opened.

In one embodiment, the latching members comprise a spheroid mounted adjacent the free, outer end of a flexible support rod and the spheroid is movable into and out of engagement with socket forming means comprising a plurality of spheroids in annular ringlike array movable radially inward and outward into and out of latching and unlatched engagement with the spheroid on said flexible rod.

For a better understanding of the present invention, reference should be had to the following detailed description taken in conjunction with the claims and drawings, in which:

FIG. 1 is a side elevational view of a typical aircraft seat including a compartment mounted in the back portion of the seat for containing emergency oxygen equipment for the passengers on the aircraft;

FIG. 2 is an enlarged fragmentary sectional view taken on a vertical plane through the aircraft seat of FIG. 1 showing the compartment and closure door thereof in enlarged detail with one embodiment of a door latching assembly constructed in accordance with the features of the present invention;

FIG. 3 is a sectional view showing the latching assembly as seen in the direction of arrows 33 of FIG. 2;

FIG. 4 is an elevational view of a compartment door on the rear of the aircraft seat;

FIG. 5 is a cross-sectional view taken substantially along line 5-5 of FIG. 3;

FIG. 6 is a cross-sectional view similar to FIG. 3 and illustrating a tool or implement being extended through an opening in the door for manually unlatching the latching assembly;

FIG. 7 is a view similar to FIG. 6 and illustrating a tool inserted through an opening in the door for manually latching the latching assembly;

FIG. 8 is an enlarged vertical sectional view similar to FIG. 2 showing another embodiment of a latching assembly constructed in accordance with the features of the present inventron;

FIG. 9 is a rear elevational view of the seat compartment of FIG. 8 as seen in the direction of arrows 9-9;

FIG. 10 is a fragmentary vertical sectional view similar to FIG. 8 but illustrating the latching assembly in an unlatched position and the compartment door in a partially open position;

FIG. 11 is a transverse sectional view taken substantially along line 11-11 ofFIG. 8;

FIG. 12 is a transverse sectional view similar to FIG. 11 taken substantially along line 12-12 of FIG. 10; and

FIG. 13 is a vertical sectional view of yet another embodiment of a latching assembly constructed in accordance with the features of the present invention and employing a modified manual unlatching system.

Referring now more particularly to the drawings, in FIG. 1 is illustrated a typical aircraft seat 10 having a base or seat 12 permanently attached to the floor 14 of an aircraft or other vehicle and an upstanding back portion 16 with an upper head rest 16a. The upstanding back portion 16 is pivotally mounted on the seat portion 12 for angular adjustment to provide for comfort of the passengers in the aircraft. In order to provide oxygen and other equipment for the passengers in case of an emergency, an enclosure or compartment 26 is mounted in the back portion 16 of the seat 10, and the compartment is adapted to contain an oxygen mask and other necessary emergency equipment as needed or required. The compartment 26 includes a pair of vertical sidewalls 11, a bottom wall 13, a rear or back wall 15, and a top wall 17, the forward edge portion 24 of which forms a jamb for a door 30. The door 30 is normally closed so that the interior of the compartment 26 is not accessible to the passengers except in an emergency. The door is hinged to the bottom wall 13 of the compartment and is pivotable from a closed position (solid lines, FIGS. 2, 6, 7, 8, and 13) to an open position (dotted lines FIGS. 1, 2, and

In accordance with the present invention, in FIGS. 2 through 7 is illustrated one embodiment of a new and improved latching mechanism 20 comprising a first latching subassembly 22 mounted on the inside surface of the compartment top wall 17 adjacent the forward edge or doorjamb 24 and a second latching subassembly 28 mounted adjacent the upper edge on the inside surface of the compartment door 30. The latching subassembly 22 includes a base 32 preferably stamped from sheet metal and provided with several elongated slots 34 for receiving sheet metal screws 38 or other suitable fasteners used for securing the subassembly in place on the compartment top wall 17. The base includes a pair of upstanding, spaced apart, parallel flanges 40 having circular openings therein to receive and support the opposite ends of an elongated pivot pin 42 on which pin is pivotally mounted a U- shaped latching lever 44.

As viewed in FIGS. 2, 6, and 7, the right-hand leg 44a of the U-shaped latching lever 44 is supported by the pin 42, and the bight or middle portion or leg 44b of the lever is movable between a generally horizontal, latched position (FIGS. 2 and 6) and an unlatched position (dotted lines in FIG. 2 and in FIG. 7). The left-hand leg 440 of the u-shaped latch lever forms a latching dog adapted to mechanically engage a slot 460 formed adjacent the free outer end of a latch lever 46 of the second latching subassembly 28. The latch lever 46 is mounted on a pivot pin 48 carried on a support bracket 50 having a base portion 52 secured to the inside surface of the compartment door 30. The bracket 50 includes a pair of upstanding flanges 54 (FIG. 3) through which the pivot pin 48 extends and the latch lever 46 is disposed to pivot between the flanges between a generally horizontal, latched position (FIGS. 2, 6 and 7) and a downwardly deflected, unlatched position (dotted lines FIG. 2) out of engagement with the latching leg 44c of the latch member 44. The lever 46 is biased to pivot in a clockwise direction (arrow A in FIG. 2) about the pivot pin 48 by a coil spring assembly 56 so that upon disengagement with the latching leg 44c of the U-shaped latch member 44, the lever 46 will automatically pivot to the unlatched position. In this position, the free outer end of the lever projects outwardly beyond the outer face of the door 30 (dotted lines FIG. 2) through a keyhole shaped slot 30a (FIG. 4) and provides a visual indication that the latching mechanism 20 is in the unlatched position (even if the door 30 remains in the closed or upright position).

In accordance with the present invention, the latch levers 44 and 46 are held or locked in mechanically latched engagement with the upper end of the latching leg 440 in the slot 46a by means of magnetic force which is supplied from permanent magnet means mounted on the bight portion 44b of the U- shaped latch lever 44. As best shown in FIG. 5, the permanent magnet holding force is established by a bar magnet 60 and a pair of North and South, L-shaped pole pieces 62 and 64 which are attached by a nonmagnetic rivet 66 to the latch lever 44. The L-shaped pole pieces 62 and 64 are formed of soft iron material which is readily magnetized, and each includes an elongated leg in contact with one face of the bar magnet 60 which is sandwiched between the legs. The outer end faces of the short legs of the pole pieces 62 and 64 lie on a common plane and are adapted to contact opposite end portions of a platelike soft iron core member 68 which is secured to the base member 32 by a pair of nonmagnetic rivets 72, or the like.

As shown in FIG. 5, the pole piece 62 is magnetized by the permanent magnet 60 and becomes anorth pole having a pole face labeled N" which is attracted to the adjacent surface of the core 68, which also becomes magnetized by the influence of the permanent magnet 60. The pole piece 64 becomes a south pole having a pole face labeled 8" which is mutually attracted to the core 68 and a completed magnetic circuit is thus provided to hold and maintain or lock the levers 44 and 46 (which may be constructed of nonmagnetic material) in mechanically latched engagement against the biasing force of the spring 56 whichexerts force tending to pivot the lever 46 into the unlatched position. The magnetic attraction between the platelike core member 68 and the respective pole pieces 62 and 64 set up by the permanent magnet 60 is sufficient to overcome the unlatching force exerted by the spring 56, and is also of sufficient strength to overcome the force of gravity acting on the latch levers as well as normal inertial forces developed because of acceleration and deceleration of the aircraft. It is significant to note that an opening pull exerted on the upper edge of the door 30 in the direction of the arrow B in FIG. 1 is resisted by the mechanical engagement between the latching levers 44 and 46 and is not dependent on magnetic holding forces. Moreover, because there is no requirement for the latch levers 44 and 46 to be made of magnetic or magnetizable materials, a wide range of suitable materials can be used to provide the needed strength. The magnetic flux path between the permanent magnet 60 and core 68 does not pass through the body of the latch lever 44 and is entirely independent thereof.

In order to manually latch or unlatch the mechanism 20, a thin knifelike tool 74 having a curved finger 74a projecting outwardly of the forward end (FIG. 7) is inserted through the slot 30a in the door 30. As the tool 74 is thrust inwardly in the direction of the arrow C, the latch lever 46 is pivoted in a counterclockwise direction from the unlatched position (dotted lines FIG. 2) to the latched or horizontal position of FIG. 7, and simultaneously the upper curved surface of the finger 74a of the tool engages a forward projection 44d on the latch lever 44 and pivots the lever in a clockwise direction until latched engagement is established between the upper end of the latch leg 44c and the slot 46a. As the latch lever 44 is pivoted in clockwise fashion from the unlatched position to the latched position (FIG. 7, dotted lines), an attractive magnetic force develops between the pole pieces 62 and 64 and the core 68. This force helps to move the lever 44 into the latched position and thereafter maintains or magnetically locks the levers 44 and 46 in latched engagement. The finger 74a of the tool can also be used to unlatch the system by placing the finger on top of the projection 44d and pivoting the tool 44 in a clockwise fashion until the magnetic attraction between the pole pieces 62 and 64 and the core 68 is no longer sufficient to hold the levers together against the force of the spring 56. In this case, when the tool 74 is withdrawn from the slot 30a, the spring 56 acts to move the lever 46 to the unlatched position (dotted lines FIG. 2). In order that a pencil or other available implement can be used for manual latching or unlatching in case of an emergency, the slot 30a in the door includes an enlarged rounded portion 30b (FIG. 5) to accommodate a pencil, screwdriver, or other implement 76. The forward face of the latching leg 44c above the projection 44d is formed with an indentation Me to receive the end of the implement for manipulating the latch lever 44 into or out of latched engagement. The U-shaped latch lever 44 is formed with a pivot stop or pivot limiting heel 44f on the upper end of the leg 44a. Engagement of the heel 44] against the base 32 (FIG. 7) limits the downward travel of the forward latching leg 44c to the position shown and thus permits ready engagement of the tool 74 or other implement for latching the assembly.

In accordance with the present invention, automatic unlatching of the latching system to permit access to the interior of the compartment 26 by the passengers is normally effected by electrical means, such as a switch or the like, operated by the pilot in the cockpit. For this purpose, an electromagnetic coil winding 80 is mounted on the core 68 and the base 32 is formed with an enlarged slot 32a in order to accommodate the winding. The coil winding comprises a relatively large number of turns wound onto the core so as to provide a magnetic polarity opposite that of the permanent magnet 60 when the coil is energized with current through the leads 80a (FIG. 3). When the coil is energized with current, the core 68 becomes magnetic in response thereto and the polarity of the core is shown by the letters N and S in FIG. 5. Because opposites repel, the electromagnetized core 68 repels the pole pieces 62 and 64 of the permanent magnet 60, and when this occurs the latch member 44 is pivoted about the pin 42 in a counterclockwise direction from the latched position to the unlatched position releasing the latch lever 46 so that the door may be opened. As long as the coil winding 80 is energized, the system cannot be relatched; however, as soon as the coil is deenergized the soft iron core 68 may again be attracted by the magnetism of the pole pieces 62 and 64 under the influence of the permanent magnet 60, and relatching is readily accomplished with the tool 74 or other implement.

The latching system 20 provides a reliable, safe system which is normally unlatched by electrical energy and which provides positive mechanical engagement to hold the compartment door closed. The latched engagement is maintained by permanent magnetic locking or holding forces which can be overcome either by electromagnetic forces in normal operation or in case of electrical failure the system can be unlatched manually. The latch system does not depend upon magnetic force for holding the compartment door in a closed position and, accordingly, can be used in a variety of different applications wherein greater, more positive mechanical latching strength is required.

Referring now to FIGS. 8-12, therein is illustrated another embodiment of a latching assembly with magnetic locking constructed in accordance with the features of the present invention and generally referred to by the reference numeral 120. The latching assembly 120 includes a first latching subassembly 122 which is mounted on the top wall 17 of the compartment 26 and a second latching subassembly 128 which is mounted on the inside surface of the compartment door adjacent the upper edge.

The second latching subassembly comprises a base assembly 130 formed of a flat washer 132 secured to the inside surface of the door 30 by spot welding or suitable fasteners. A second washer 134 with with a raised central portion is secured to the flat washer 132 to provide a recess 136 (FIG. 8) in order to accommodate a disk 138 which is attached to the inner end of a support post or rod 140 which projectsoutwardly of the inside surface of the door 30 at substantially right angles thereto. The space or recess 136 is larger than the space occupied by the disk 138 and headed inner end of the support post or rod 140, and the raised washer 134 is provided with a central aperture slightly larger than the diameter of the rod to permit some free play or angular movement of the rod with respect to an axis or median line perpendicular to the door surface. The outer end of the rod 140 is headed over against a spherical latch member or ball 142 which is secured in place adjacent the free, outer end of the rod by the heading operation. In order to maintain the rod in a generally perpendicular attitude relative to the door 30, yet permit some free play or angular movement of the outer end of the rod within reasonable limitation, a stabilizing spring 144 is coaxially aligned on the rod adjacent the inner end portion thereof. The spring 144 is formed with a plurality of helical convolutions which progressively decrease in diameter from a maximum adjacent the washer base 134 to a minimum outwardly thereof on the body of the rod midway between the ends thereof. When the spherical latch member 142 at the outer end of the rod is deflected from the normal position wherein the rod is normal to the door 30, the spring 144 acts to restore or return the rod and ball to the normal or median position.

In accordance with the present invention, the first latching subassembly 122 includes a socketlike assembly generally indicated as and adapted to receive and latchingly engage the single spherical ball or enlargement 142 on the free outer end of the support post 140 of the latching subassembly 128. The socketlike latching assembly 150 includes a cylindrical, hollow sleeve 152 open at both ends and having a radially inwardly extended flange 154 at the forward end which provides a retaining ring at the forward end of the sleeve. A coaxially aligned, frustoconically shaped guide surface is provided on the forward face of the flange 154 in order to aid in axially centering the spherical latch member 142 as it is moved in an axial direction into the interior of the socket assembly 150. The cylindrical sleeve 152 is supported from a pair of side flanges 156 disposed on opposite sides thereof and a pair of ribs 158 (FIG. 13) connect the sleeve to the flanges 156.

The rearward end of the sleeve 152 is partially closed by a cap member 160 having a central aperture therein in order to accommodate the forward end portion of an elongated, axially movable latch plunger 162 having an enlarged forward end portion 164 which is mounted to slide within the sleeve. The rearward end portion of the latch plunger includes a reduced diameter neck 162a and a sleeve 167 is mounted adjacent the outer end of the neck to act as a grommet or bushing during reciprocal sliding movement of the plunger in a supporting aperture 170a formed in an upstanding rear flange 170 of a support bracket for the subassembly 122. The enlarged forward end portion 164 of the slidable latch plunger 162 is movable between a forward or latched position as shown in FIGS. 8 and 11 to a rearward or unlatched position shown in FIGS. 10 and 12 wherein latching engagement with the ball 142 of the latching subassembly 128 is released. The latching plunger 162 is biased toward the rearward or unlatched position by means of a coil spring 172 disposed between the rear end closure wall 160 on the sleeve 152 and a cross pin 174 (FIG. 8) extended transversely through the body of the plunger 162.

In accordance with the present invention, the enlarged forward end portion 164 of the latching plunger 162 is formed with a deep axial recess or counterbore 164a which provides space for receiving and accommodating the spherical latch ball 142 of the latching subassembly 128 when the latching subassemblies 122 and 128 are in engaged latched position, as best shown in FIG. 8. A second, more shallow recess or counterbore l64b of larger diameter is formed in the enlarged head portion 164 on the plunger 162, and a frustoconical outer surface l64c is formed to extend outwardly and forwardly of the second counterbore l64b.

In order to provide mechanical latching engagement for holding and retaining the spherical ball 142 in latched engagement with the latching subassembly 122, a plurality of spherical latch balls 166 are mounted in circumferentially spaced array within the sleeve 152. Each of the latch balls 166 is formed with a diametrically disposed drilled passage 166a therethrough in order that a spring-steel C-ring 168 may be extended or threaded therethrough. The C-ring 168 is constructed of spring wire and has a nominal diameter when unstressed, as shown in FIG. 12, which diameter is considerably larger than its diameter in a compressed or stressed condition, as shown in FIG. 11. When the enlarged head portion 164 of the latching plunger 162 is moved into the forward or latched position (FIG. 8), the latching balls 166 are forced by the frustoconical surface 164c into the counterbore 164b, which is smaller in diameter than the interior bore of the sleeve 152.

When this occurs, the balls 166 are moved radially inwardly and the C-ring 168 is compressed to provide latching engagement between the ring of balls 166 of subassembly 122 and the single ball latch 142 of the latching subassembly 128. In this condition, a low friction mechanical latched engagement is established between the spherical ball surfaces for holding the door 30 in the closed position.

In order to unlatch the latching assembly 120, the plunger 162 is moved rearwardly to the unlatched position as shown in FIG. 10, and the enlarged head portion 164 is shifted to the rear end of the sleeve 152. When this occurs, any outward pull on the ball 142 and expansion of the C-spring 168 to its normal unstressed position moves the balls 166 radially outwardly and out of engagement with the single latch ball 142, as shown in FIG. 12. When this occurs, the door 30 may be freely opened and pivoted to provide immediate access to the interior of the compartment 26. Latching mechanical engagement between the latching subassemblies 122 and 128 is maintained by tangential contact between the spherical surfaces of the single ball 142 of the latching subassembly 128 and a plurality of balls 166 contained in the socket forming sleeve 152 of the latching subassembly 122. Because of this arrangement, exactly accurate alignment between the subassemblies 122 and 128 is not a necessity and close manufacturing tolerances of the individual assemblies are not required. The mechanical holding ability of the latching assembly 120, however, is not impaired even though close tolerances are not required.

The spring 172 biases the latch plunger 162 to the rear or the unlatched position and, in accordance with the present invention, the plunger is normally maintained in the forward or latched position by means of a permanent magnet member 176 which is sandwiched between the longer legs, respectively, of a pair of L-shaped north and south pole pieces 178 and 180 as best shown in FIG. 13. The pole pieces are made of soft iron which is readily magnetized by the permanent magnet 176 and the permanent magnet and the pole pieces are mounted as a unit on a nonmagnetic sleeve or grommet 181 which is carried on the reduced diameter neck portion 162a at the rear end ofthe plunger 162 (FIG. 8).

As shown in FIG. 13, the north pole piece 178 includes a short leg having an end face in a common plane, with the end face of the short leg of the south pole piece 180. The aligned end faces of the respective north and south pole pieces are adapted to contact and exert magnetic attraction on a pair of fixed pole members 182 and 184 (FIG. 13), respectively, which are mounted at opposite ends ofa flat core member 186 (FIG. 8) of an electromagnetic coil 190. Rivets 188 or other suitable fastening means (FIGS. 8 and 13) are provided to secure the core 186 and the pole pieces 182 and 184 together. These members are formed of soft iron or other material which is readily magnetizable but does not retain permanent magnetism to any extent.

The coil winding 190 and circuitry connected thereto are polarized so that when electric current is supplied to the coil the pole piece 182 becomes a north pole and pole piece 184 becomes a south pole. With this polarity, the electromagnetized pole pieces 182 and 184 and the permanent magnet pole pieces 178 and 180 repel each other causing the plunger 162 to shift to the rear and unlatch the mechanism.

When no current is supplied to the electromagnetic coil 190, the core 186 and pole pieces 182 and 184 are magnetized by the permanent magnet 176 acting through the L-shaped pole members 178 and 180. Attractive forces are developed between pole members 182 and 184 and the pole pieces 178 and 180 so that a completed series magnetic holding circuit is established through the members 176, 178, 180, 182, 184, and 186 for holding the latch plunger 162 in the forward or latched position against the force of the bias spring 172. It should be remembered, however, that it is the mechanical latching engagement between the ball 142 and ring of balls 166 which provides the mechanical latching for holding the door 130 in the closed position, and this mechanical force is many times greater than the magnetic holding or locking force between the pairs of pole pieces 178 and 180 and 182 and 184. The latching assembly 120 thus provides a system having mechanical latching with magnetic locking or holding for maintaining the latch assembly in the engaged or latched position.

In normal operation, when it is desired to unlatch the assembly 120 so that the door 30 can be opened, electric current is supplied to the coil winding 190 causing the core 186 to be magnetized and the pole pieces 182 and 184 to become electromagnetized as north and south poles, respectively. When this occurs, magnetic repelling forces are developed between the pairs of poles 182 and 178 and the pairs 184 and 180. These repelling forces overcome or replace the permanent magnet holding force and shift the plunger 162 and head portion 164 rearwardly within the socket or sleeve 152 from the latched position of FIG. 8 to the unlatched position shown in FIG. 10. When this occurs, the ring or array of latching balls 166 is free to shift radially outwardly as the C-shaped spring 168 expands. Latching engagement between the balls 166 and the single latch ball 142 of the latching subassembly 128 is then released, permitting the door 30 to be opened freely, as shown in FIG. 10. Because of the socket and ball latching arrangement, close alignment between the latching subassemblies 122 and 128 is not a necessity because the frustoconical guide surface on the forward face of the flange 154 of the socket guides the ball 142 and support stem into axial alignment with the socket sleeve 152 as the door is closed. After the door has been closed and the ball 142 is centered with the deep counterbores 164a and'164b in the head portion 164, the latch plunger 162 is shifted forwardly against the force of the bias spring 172 until the attractive magnetic forces developed by the permanent magnet 176 between the pole pieces 178 and 180 and the adjacent pole members 182 and 184 are sufficient to hold and retain the flanges in latched engagement as shown in FIG. 8. This attractive retaining force is large enough to overcome the biasing force of the spring 172 and the force of the spring 168, and as the head portion 164 shifts forwardly in the sleeve 152 the balls 166 are cammed inwardly by the conical surface 1646 into the counterbore 164b. The surface of the counterbore l64b acts as a containment surface preventing radially outward travel of the balls 166. The balls 166 are thus maintained in contact against the ball 142 and prevent the door 30 from being opened.

Manual unlatching of the assembly 120 is accomplished by a pull ring 192 accessible through an opening in the rear wall 15 of compartment 26. The pull ring 192 is pivotally connected to the sleeve 167 on the rear end of the latch plunger 162 and is readily grasped by the finger and moved rearwardly to mechanically unlatch the assembly when desired, or if the electrical system fails. By manually moving the pole pieces 178 and 180 far enough rearwardly to diminish the magnetic attractive force between these pole pieces and their counterparts 182 and 184, the force of the spring 172 is then available to hold the plunger 162 in the unlatched position until it is relatched. When it is desired to relatch the latching system 120, the door 30 is closed so that the rod 140 and ball 142 of the latching subassembly 128 is positioned in centered alignment in the socket sleeve 152. The plunger 162 is moved forwardly against the bias of the spring 172 until the magnetic pole pieces 178 and 180, which are magnetized by the permanent magnet 176, exert sufficient magnetic attraction on the pole members 182 and 184 to draw the plunger 162 forwardly into the latched position. The latching assembly 120 is maintained in the latched position of FIG. 8 until it is unlatched either by electromagnetic energy supplied by energizing the coil or by manually moving the plunger 162 rearwardly as by pulling on the ring 192. The latching assembly 120 thus provides a low cost, extremely reliable latching system for use with an aircraft oxygen compartment.

Referring now to FIG. 13, a difierent type of manual unlatching mechanism is provided, which includes an L-shaped lever 196 pivotally mounted on a pin 198. One leg of the lever is attached to the pin 174 on the plunger 162 and the forwardly extending leg of the lever terminates approximately even with the front face of the door 30. The forward end of the forward leg of the lever 196 is accessible through an opening 301: fonned in the door 30 so that the lever may be moved to manually unlatch or latch the latching assembly 120.

Although the present invention has been described with reference to several illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A latching assembly for a door swingable toward and away from a doorjamb, said latching assembly comprising a pair of mechanically engageable latch means mounted on said door and jamb, respectively, and movable relatively between an engaged, latched position and a disengaged, unlatched position, permanent magnet means for retaining mechanically latched engagement between said pair of said latch means in said latched position, electromagnet means having a polarity while energized opposing said permanent magnet means for overcoming the retaining force thereof permitting relative movement between said pair of said latch means to said unlatched position so that said door can be opened, one of said pair of said latch means including a pair of relatively movable members, said permanent magnet means mounted on one of said members and said electromagnet means mounted on the other of said members.

2. The latch assembly of claim 1 wherein said holding force exerted by said permanent magnet means extends in a direction generally normal to the direction of movement of I said door toward and away from said doorjamb.

3. The latch assembly of claim 1 wherein one of said latch members is mounted for pivotal movement relative to the other, said permanent magnet means providing magnetic force for normally biasing said pivotally mounted latch member toward said latched position to engage said other latch means until said force is overcome by opposing magnetic force developed by energization of said electromagnet means.

4. The latch assembly of claim 1 including spring means for biasing said one latch means away from said latched position against the force of said permanent magnet means.

5. The latch assembly of claim 3 wherein said pivotally mounted latch member includes stop means e ngageable with said other member for limiting the pivotalinovement away from said latched position.

6. The latch assembly of claim 1 wherein the other of said latch means includes an elongated stem supported at one end in cantilever fashion and an enlargement mounted adjacent the outer free end of said stem for latching engagement with said one latch means in said latched position.

7. the latch assembly of claim 6 wherein said enlargement comprises a spherical ball mounted on said stern, said stem being laterally flexible adjacent said outer free end and movable axially relative to said one latch means into and out of latching engagement therewith.

8. The latch assembly of claim 7 wherein said one latch means comprises socket forming means including a plurality of circumferentially spaced latching balls movable radially of the axis of said stem into and out of latching engagement with said enlargement on said stem and means for moving said balls into and out of latching engagement with said enlargement.

9. The latching assembly of claim 8 wherein said one latch means includes a hollow sleeve for containing said balls and an elongated plunger for axial sliding movement relative to said sleeve permitting radial movement of said balls in response to the axial position thereof, said permanent magnet means normally urging said plunger into an axial position wherein said balls are in said latched position.

10. The latching assembly of claim 9 wherein the force exerted by said electromagnetic means while energized is active to move said plunger into a second axial position permitting said balls to move radially outward out of latched engagement with said enlargement.

11. The latch assembly of claim 10 wherein magnetic force attraction between said permanent magnet means and said latch means is in a direction generally parallel of said plunger.

P040511 UNITED STATES PATENT OFFICE CERTIFICATE OF QORRECTIUN Patent No. 3,658,370 Dated April 25, 1972 Inv n fl willie-1m 5., Wang It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

we w Column 10, line 22, after "plunger" there should be inserted -mounted-.

Signed I and sealed this 20th day of March 1973 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I Patent No. 3,658 Dated p il 25, 1972 Will iam S .T Wang Inventofls) It is certified that error appears in the above-identified patent I and that said Letters Patent are hereby corrected as shown below:

. In, the grant (only) insert the attached sheet Signed and sealed this 20th day of March 1973 (SEAL) Attest:

EDWARDM.FLETCHER,JR. ROBERT GOTTSCHAL'K Attesting Officer I Commissioner of Patents FORM T504050 (10-69) uscoMM-Dc scam-peg t U.5T GOVERNMENT PRINTING OFFICE: 1959 O365'"334, 

1. A latching assembly for a door swingable toward and away from a doorjamb, said latching assembly comprising a pair of mechanically engageable latch means mounted on said door and jamb, respectively, and movable relatively between an engaged, latched position and a disengaged, unlatched position, permanent magnet means for retaining mechanically latched engagement between said pair of said latch means in said latched position, electromagnet means having a polarity while energized opposing said permanent magnet means for overcoming the retaining force thereof permitting relative movement between said pair of said latch means to said unlatched position so that said door can be opened, one of said pair of said latch means including a pair of relatively movable members, said permanent magnet means mounted on one of said members and said electromagnet means mounted on the other of said members.
 2. The latch assembly of claim 1 wherein said holding force exerted by said permanent magnet means extends in a direction generally normal to the direction of movement of said door toward and away from said doorjamb.
 3. The latch assembly of claim 1 wherein one of said latch members is mounted for pivotal movement relative to the other, said permanent magnet means providing magnetic force for normally biasing said pivotally mounted latch member toward said latched position to engage said other latch means until said force is overcome by opposing magnetic force developed by energization of said electromagnet means.
 4. The latch assembly of claim 1 including spring means for biasing said one latch means away from said latched position against the force of said permanent magnet means.
 5. The latch assembly of claim 3 wherein said pivotally mounted latch member includes stop means engageable with said other member for limiting the pivotal movement away from said latched position.
 6. The latch assembly of claim 1 wherein the other of said latch means includes an elongated stem supported at one end in cantilever fashion and an enlargement mounted adjacent the outer free end of said stem for latching engagement with said one latch means in said latched position.
 7. the latch assembly of claim 6 wherein said enlargement comprises a spherical ball mounted on said stem, said stem being laterally flexible adjacent said outer free end and movable axially relative to said one latch means into and out of latching engagement therewith.
 8. The latch assembly of claim 7 wherein said one latch means comprises socket forming means including a plurality of circumferentially spaced latching balls movable radially of the axis of said stem into and out of latching engagement with said enlargement on said stem and means for moving said balls into and out of latching engagement with said enlargement.
 9. The latching assembly of claim 8 wherein said one latch means includes a hollow sleeve for containing said balls and an elongated plunger for axial sliding movement relative to said sleeve permitting radial movement of said balls in response to the axial position thereof, said permanent magnet means normally urging said plunger into an axial position wherein said balls are in said latched position.
 10. The latching assembly of claim 9 wherein the force exerted by said electromagnetic means while energized is active to move said plunger into a second axial position permitting said balls to move radially outward out of latched engagement with said enlargement.
 11. The latch assembly of claim 10 wherein magnetic force attraction between said permanent magnet means and said latch means is in a dIrection generally parallel of said plunger. 